With reference to FIG. 1, the prior art handhold mobile devices, such as smart phones and personal digital assistant 1, have a tendency of having compact size and light weight. The interfere cards used are SD cards (secured digital cards) instead of the PCMCIA cards or compact flash cards. For example, receivers 11 of the global positioning system uses SD cards, or MMCs (multi-media cards) instead of the PCMCIA cards or compact flash cards.
The handhold mobile device has a compact size. Thus, generally it has only one slot for receiving for example, a SD card or an MMC or a memory stick card, while a general satellite receiver 11 must be used with electronic map which needs a larger amount memory space. Thereby the map cannot be contained in the handhold mobile device. The user stores the electronic map in the SD card or an MMC or a memory stick card. However since the slot has received the memory and thus it can be used with the satellite receiver 11. Thereby the user can only select to use the memory card 10 singly or use the satellite receiver singly. They cannot be used at the same time.